Conventionally, a heat pump including a compressor, a plurality of radiators, an expansion valve and an evaporator has been proposed (for example, refer to Patent Literature 1 and Patent Literature 2).
For example, in Patent Literature 1, a heat pump including a primary-side refrigerant circuit in which a compressor, a plurality of gas coolers, an expansion valve, and an evaporator are connected by refrigerant piping, and a secondary-side refrigerant circuit in which a gas cooler and a circulation pump are connected by piping is proposed. In this heat pump, water flowing through the secondary-side refrigerant circuit is heated in the gas cooler, and the heated water is used in hot water supply, cooling and heating, floor heating, and the like.
In Patent Literature 1, a method for connecting (serial connection and parallel connection) the gas coolers in accordance with the influx temperature of water flowing into the gas coolers is proposed. The gas coolers are disposed based on a connection method in accordance with the influx temperature of water flowing into the gas coolers, and COP is improved by utilizing the heat energy of a refrigerant flowing through the gas coolers in a cascaded manner.
For example, in Patent Literature 2, a heat pump that performs refrigeration and freezing in which a high order-side refrigeration system, which assists the heat transfer of a low order-side refrigeration system, is connected to a radiator outlet of the low order-side refrigeration system is proposed. In this heat pump, in a cooling operation such as refrigeration or freezing, refrigerant in an outlet of an outdoor heat exchanger is cooled using the high order-side refrigeration system in order to improve the refrigeration capacity.